In conventional buoys, the float is integral with a tube containing the plunger. The plunger is separated from its tube by the release of an end plate under the effect of the forces applied at the moment of impact with the water.
Now, the release can fail to take place when the buoy hits the water at too great an angle from the normal.
In the acoustic buoy according to the invention, the plunger is separated from the float even if the angle of incidence in relation to the surface of the water is very oblique at moment of impact.